The present invention relates generally to a blow molded condensing heat exchanger made of a norbornene polymer having thermal, chemical and physical resistant to the conditions of a condensing heat exchanger.
Condensing heat exchangers are employed in condensing furnaces to increase efficiency. The condensing heat exchanger cools the heating fluid to a temperature below the dew point. As the temperature drops below the dew point, a liquid condensate, water vapor, condenses from the heating fluid. As the liquid condensate condenses, heat is transferred from the water vapor to the air to be heated. As more heat is produced, the efficiency of the system is increased.
Polypropylene films are commonly utilized to make a laminated condensing heat exchanger material to prevent corrosion of the heat exchanger by the water vapor liquid condensate. In prior condensing heat exchangers, the film is formed by melted polypropylene pellets which are extruded or cast to form a film. The metal surface of the condensing heat exchanger is then heated. The film is applied to the heated condensing heat exchanger, and the heated surface slightly melts the film, adhering the film to the condensing heat exchanger. A roller passes over the surface of the film to further adhere the film to the condensing heat exchanger. Alternatively, the film is adhered to the metal with an appropriate adhesive and primer.
Blow molding and extrusion are known process commonly employed to make bottles or tubes. Polyester is a polymer which is often utilized during blow molding or extrusion. However, polyester does not have acceptable physical, chemical or thermal resistance to the conditions of a condensing heat exchanger.
There are several drawbacks to the polypropylene film of the prior art. For one, the metal can corrode if the film is not continuous or if there are holes in the film. Additionally, it is costly to manufacture and apply the prior art film to the metal heat exchanger. Therefore, it would be advantageous to form a condensing heat exchanger entirely out of a corrosion resistant material.
Hence, there is a need in the art for a condensing heat exchanger made of a polymer which is capable for withstanding the conditions of a condensing heat exchanger.